Paris Hilton recently told Ryan Seacrest that she's sure her beau Cy Waits will pop the question. And based on a recent shopping adventure, it sounds like Waits could be getting down on one knee sooner than later.

A source tells PEOPLE that Hilton, who just celebrated her 30th birthday, accompanied Waits to luxury jewelry store Jacob & Co. in New York on Friday, where the duo checked out some serious bling.

"They shopped for engagement rings," the source says. "They were really cute together. Paris was making comments about the rings and joking that her ring has to be at least 24 carats."

Although the lovebirds – who began dating last summer – did not leave with an engagement ring, Hilton did not leave empty-handed.